Pipe travelling apparatus with alignment control

ABSTRACT

A conduit travelling apparatus is capable of crawling through a conduit for performing certain operation by a stepwise sequence of alternating sequences of expanding and contracting the length of the body while bracing each end alternately. The apparatus provides a self aligning element for correcting rotation of such apparatus due to powered operations it may perform, or any natural tendency to twist as it progresses. The self aligning element includes steering elements overseen by a control system which helps return the travelling apparatus to a preferred alignment during its forward or rearward travel.

TECHNICAL FIELD

The invention relates generally to self-propelled vehicles for use inconduits, typically remote-controlled vehicles with apparatus forcleaning conduits. In particular it addresses issues of rotation of theapparatus as it travels along a conduit.

BACKGROUND ART

The applicant has previously filed patent applications (WO 2005/061944A1—PCT/NZ2004/000330) for self propelled apparatus which travels along apipe. In summary this apparatus comprises a forward section, and arearward section, connected in a manner in which the two sections can beforced apart or drawn together. Movement along a conduit is achieved byextending clamping elements on the rearward section to engage the innersurface of the conduit. Clamps present on the forward section arereleased and the connection between the sections is extended so theforward section moves forward. The clamps on the forward section arethen engaged against the inner surface of the conduit, whilst those ofthe rearward section are released. The connection between the sectionsis then contracted and the rearward section is drawn forward, whereuponits clamps may be re-extended to engage the inner surface of theconduit. Once the vehicle is so secured (i.e. clamped) variousoperations—such as rotary cleaning on the inside of the conduit—maycommence.

In addition the pipe traveller typically has wheel sets on each sectionwhich engage the inner walls of the conduit as the clamping elements ofa section are withdrawn from the conduit walls. This helps to keep theapparatus centred, whilst the wheels also facilitate smooth movementalong the conduit as each section moves therealong.

In practice it has been noted that a problem can occur during operationand travel of the apparatus along a conduit. This problem relates torotation of the pipe-travelling apparatus about its long axis as ittravels. The consequence of such rotation is that it can affect theoperation or performance of certain attached accessories and equipmentif the pipe-travelling apparatus is no longer in a preferred levelposition. For instance, waste slurry and cleaning liquid may becollected (for waste or recycling) by a suction mouth which is typicallylocated at the bottom of the pipe travelling apparatus. Rotation of thepipe travelling apparatus can therefore interfere with its operation.

Rotation can also cause other issues, such as the twisting together ofcables and lines which can trail the apparatus—such lines may carryelectronic information, control data, video signals, electrical power,hydraulic fluid, etc. Twisting of the lines about each other can causeproblems such as potential damage to, or constriction of, lines.Additionally, twisting the lines about each other stiffens the bundlemaking it less flexible and harder for the apparatus to draw aroundcurves and bends in the conduit.

Research by the applicant has confirmed that this rotation can be anatural consequence of the travel of the apparatus along a conduit.Minor obstructions or irregularities in the conduit can bias theapparatus to rotate relative to the conduit as it travels. Minorvariations in the action of moving components, especially over time, canalso contribute to such rotation—in the same manner that most peoplelost in a forest will walk in a circle (due to one leg being naturallyslightly shorter than the other) even though they believe they arewalking in a straight line.

However, one of the greatest effects is a consequence of the action ofcertain accessories on typical embodiments of pipe travelling apparatus,notably those which are rotational in action. The best demonstrativeexample is a rotating cleaning head assembly, the rotational axisthereof being the same as that of the pipe travelling apparatus. Suchapparatus is typically stopped (or substantially slowed) as theapparatus moves forward, and restarted when the apparatus is stopped andclamped in its new position. Most of these units have reasonableinertia, and sufficiently high rotational momentum when operating thatthey apply a significant rotational force to the pipe travellingapparatus when they are started. This back force is sufficient to causesome rotation of the pipe travelling apparatus about its long axis, thedegree of this effect being determined largely by how well the pipetravelling apparatus is clamped against the inside of the conduit, thisin turn being affected by factors such as irregularities andcontaminants on the inside of the conduit; soiling of the clampingelements by continued use or by travel through the conduit; fluidspresent in the conduit, and so on.

Accordingly there is a real problem which can affect the performance andoperation of pipe travelling apparatus, particularly of the typedescribed above.

Accordingly it is an object of the present invention to consider theforegoing problems and address rotational issues during the traveland/or use of pipe travelling apparatus within a conduit.

At the very least, it is an object of the present invention to providethe public with a useful choice.

Further aspects and advantages of the present invention will becomeapparent from the ensuing description which is given by way of exampleonly.

DISCLOSURE OF THE INVENTION

According to one aspect of the present invention there is providedconduit travelling apparatus for travelling through a conduit, saidconduit travelling apparatus comprising two travelling body portions,each with associated wall engaging clamping means, and said travellingbody portions connected by extensible drive means capable of moving saidtravelling body portions towards and away from each other;

-   -   at least one said travelling body portion including at least one        steerable contact portion which can be brought to bear against        the inside of a conduit as the travelling body portion moves        with respect to the conduit;    -   a said steerable contact portion including at least one conduit        engaging element for contacting an inner surface of said        conduit;    -   the arrangement being such that said conduit engaging element        can exert a steering force against said inner surface of the        conduit when its carriage portion bears against and travels        along same;

the conduit travelling apparatus also including and/or communicable withinclination and orientation control means comprising inclinationdetermining means, for determining the rotational inclination of theconduit travelling apparatus;

said inclination and orientation control means consequently controllingone or more said steerable contact portions associate with the conduittravelling apparatus.

According to another aspect of the present invention there is providedconduit travelling apparatus, substantially as described above, havingan extensible body in which:

said two travelling body portions comprise a forward body portion and arearward body portion separated by a powered telescoping connection ofvariable and controllable length, the powered telescoping connectioncharacterized that the distance between said forward and rearward bodyportions is controllably alterable;

each of said forward body portion and rearward body portion including awall-engaging mechanism;

each wall engaging mechanism comprising a plurality of radiallypivotable legs, each connected to a said body portion at one end andhaving a wall-engaging foot at the distal end;

for each wall engaging mechanism, all of the radially pivotable legswith wall engaging feet connecting to a common actuator, said commonactuator controlling the radially extended position of said radiallypivotable legs between retracted and extended positions;

the wall engaging mechanism on either or both of said forward andrearward body portions including at least one retractable wheelarrangement, a said retractable wheel arrangement comprising a pluralityof wall engageable wheel assemblies each coupled to a radially pivotingwheel bracket;

said radially pivotable legs and said radially pivoting wheel bracketsof a wall engaging mechanism coupled, the coupling preventing both of i)said radially pivotable legs and ii) said radially pivoting wheelbrackets being simultaneously in a fully radially extended position.

According to another aspect of the present invention there is providedconduit travelling apparatus, substantially as described above, in whichthere is inclination determining means associated with each travellingbody portion.

According to another aspect of the present invention there is providedconduit travelling apparatus, substantially as described above, in whichthe inclination and orientation control means determines the rotationalinclination of the conduit travelling apparatus relative to one or morepreferred reference orientations.

According to another aspect of the present invention there is providedconduit travelling apparatus, substantially as described above, in whichthe inclination and orientation control means determines the steeringaction required to correct the rotational inclination of the conduittravelling apparatus towards a preferred rotational inclination.

According to another aspect of the present invention there is providedconduit travelling apparatus, substantially as described above, in whichthere is controllable steering drive means associated with a steerablecontact portion.

According to another aspect of the present invention there is providedconduit travelling apparatus, substantially as described above, in whichthe steering drive means is driven by one or methods in the followinglist: hydraulically powered, electrically powered, and pneumaticallypowered.

According to another aspect of the present invention there is providedconduit travelling apparatus, substantially as described above, in whicha conduit engaging element is pivotably connected the steerable contactportion, to provide a steering action.

According to another aspect of the present invention there is providedconduit travelling apparatus, substantially as described above, in whichthe steerable contact portion comprises a carriage.

According to another aspect of the present invention there is providedconduit travelling apparatus, substantially as described above, in whichthe steerable contact portion is pivotably connected to the travellingbody portion so as to provide a steering action.

According to another aspect of the present invention there is providedconduit travelling apparatus, substantially as described above, in whicha conduit engaging element comprises one or more members for thefollowing list: wheels, rollers, rotating track assemblies, and skids.

According to another aspect of the present invention there is providedconduit travelling apparatus, substantially as described above, in whichthe inclination and orientation control means continuously orrepetitively adjusts the degree of steering of a steerable contactportion during motion of a travelling body portion.

According to another aspect of the present invention there is providedconduit travelling apparatus, substantially as described above, in whicheither or both a steerable contact portion and conduit engaging elementis retractable so as to not engage an inner surface of said conduit.

According to another aspect of the present invention there is providedconduit travelling apparatus, substantially as described above, in whichthe pressure by which a conduit engaging element bears against an innersurface of the conduit can be varied.

According to another aspect of the present invention there is providedconduit travelling apparatus, substantially as described above, in whichthe inclination and orientation control means adjusts the pressure bywhich a conduit engaging element bears against an inner surface of theconduit as part of its control over the steering and changing of theinclination of a travelling body portion.

Typically the conduit travelling apparatus may be of a type similar tothat disclosed in the applicant's earlier application—WO 2005/061944A1—PCT/NZ2004/000330. For simplicity of description, the presentinvention will be described with reference to the machine described inthat application, though may be applied to travelling devices ofdifferent specific design.

The travelling body portions of the present invention relate to theforward and rearward portions of the earlier device, while theextensible drive means of the present invention is equivalent to theextensible means of the earlier device.

As for the earlier device, each travelling body portion includes aclamping arrangement essentially comprising a plurality of arms withwall contacting feet on each. Preferably these feet have a reasonablyhigh coefficient of friction when pressured against the wall, as theyserve to hold the apparatus in place when certain operations (such ascleaning) are performed, as well as bracing the travelling body portionwhile the other moves forwardly.

In the previous device each travelling body portion included wheelswhich could bear against the inner wall/surface of the conduit when thewall contacting feet were retracted. The present invention also relieson conduit engaging elements which bear against the inner surface of theconduit when the wall contacting feet are withdrawn, though theseconduit engaging elements need not be wheels—they may comprise one ormore of any of a set of engaging elements comprising: wheels, rollers,skids, and continuous tracks (e.g. as used on tracked vehicles such asbulldozers).

A primary difference between the present and previous invention is thatthe conduit engaging elements of the present invention can apply asteering force to the conduit's surface as they travel along same. Thissteering force can be used to steer the travelling body portions as theymove along a conduit. As there is limited scope for movement within acircular conduit, the preferred consequence of the steering effect is torealign the conduit travelling apparatus to its normal or a preferredorientation.

To effect this, inclination and orientation control means is also used,this typically comprising one or more inclinometers or other devicesproviding information about the rotational orientation of the conduittravelling apparatus. This orientation may be determined in relation totrue horizontal (this being perpendicular to the force of gravity), atrue vertical (this being substantially the direction of gravitationalforce), to a reference point in the circumference of the pipe, or tosome other reference point—in a vertical conduit the inclination andorientation control means may orientate itself with respect to themagnetic poles or some other signal—including GPS data. In any event,the inclination and orientation control means can determine thedeviation in inclination or rotation of the conduit travelling apparatus(or part thereof) from a comparison or reference value. Various forms ofinclinometers and directional sensors may be used, including thoseutilising a gyroscope as a reference comparison point.

The inclination and orientation control means will ideally thendetermine what direction and degree of steering action, by one or moreconduit engaging elements, is required to allow the conduit travellingapparatus (or part thereof) to attain the desired inclination within theconduit. This may be calculated in relation to the distance to betravelled—either in a single step forward, or over several—the lattermay be preferred when it is known the device is to move forward byseveral steps.

To achieve this, typically the steering is achieved by one or moresteerable contact portions (typically on a travelling body portion)which in turn include one or more conduit engaging elements. Steeringcontrol is ideally powered, some options including hydraulic, pneumatic,and electrically powered mechanisms. Hence, the inclination andorientation control means can then control the degree of steeringdirection and/or force acting on the conduit's surface by a conduitengaging element.

In the situation where there are multiple conduit engaging elements,and/or multiple steerable contact portions, independent control over thesteering action of each element and/or contact portion may be providedfor. However, where there are multiple elements and/or contact portionsassociated with a travelling body portion, it is envisaged that thesimpler concept of controlling each of these equivalently (i.e.synchronised with each other) will be preferred—e.g. each contactingwheel in a body portion steers in the same direction by substantiallythe same amount.

As can be envisaged, various steering strategies can be employed toalign/re-align conduit travelling apparatus.

The steerable contact portion may take many forms. Typically thesteerable contact portion comprises a carriage which supports one ormore conduit engaging elements. Conduit engaging elements may besteerable with respect to the carriage. The carriage/steerable contactportion may be steerable with respect to the travelling body portionwith which it is associated. Various combination of the carriage, andthe conduit engaging elements, may be steerable or fixed—so long as thea steering force can be applied to the inner surface of the conduit asthe steerable contact portion moves along the conduit.

The steerable contact portion(s) may be affixed directly to the bodystructure of the travelling body portion, or mounted on an arm whoseorientation or length (etc.) can be altered to bring the steerablecontact portion into contact with the inner surface of the conduit.

While provision may be made for the steerable contact portion(s) and/orconduit engaging element(s) to be withdrawn from contact with the innersurface of the conduit, some embodiments of conduit travelling portionsmay have one or more conduit engaging elements in contact with the innersurface of the conduit at all times. Typically, however, the arrangementshould allow for the conduit engaging elements to accommodateirregularities and features which may be present on the inner surface ofa conduit as they travel therealong.

Aspects of the present invention will now be described by way of exampleonly with respect to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Further aspects of the present invention will become apparent from thefollowing description which is given by way of example only:

FIG. 1 is a pictorial view of a first embodiment of the vehicle of theapplicant's previous application:

FIG. 2 is a detail of the forward member of the vehicle of FIG. 1;

FIGS. 3 a and 3 b are details of the rearward member of the vehicle ofFIG. 1, and

FIG. 4 is a pictorial view of a second embodiment of the vehicle of theapplicant's prior application;

FIG. 5 is a pictorial view of a wall engaging mechanism of the vehicleof FIG. 4;

FIG. 6 is a longitudinal cross-sectional view of a wall engagingmechanism of the vehicle of FIG. 4;

FIG. 7 is longitudinal cross-sectional view of the vehicle of FIG. 4;

FIG. 8 is a side view of the vehicle of FIG. 4 shown exploded,

FIG. 9 is a perspective view of an embodiment of a steerable contactportion according to the present invention,

FIG. 10 is a side diagrammatic view of an alternative embodiment of acarriage portion according to the present invention, and

FIG. 11 is a schematic view of a preferred embodiment of a controlsystem according to the present invention

BEST MODES FOR CARRYING OUT THE INVENTION

Reference will be made, by way of example only to the travellingapparatus of the applicant's previous patent application. This vehiclewill be used as a reference vehicle to illustrate the principles of thepresent invention.

FIG. 1 illustrates an embodiment of conduit travelling apparatus fittedwith conduit cleaning apparatus. The apparatus generally comprises aforward travelling body portion 1 mounted to a hydraulic cylinder 2which represents the extensible drive means. Also present, mounteddistally to the cylinder 2 is a rearward travelling body portion 3. Apower actuated wall-engaging arrangement (described further withreference to FIGS. 2, 3 a and 3 b) is provided on both the forward andrearward body portions 1 and 3 for extending and retracting feet 5′ and5 respectively for selectively engaging the inner wall of a conduit 14(see FIG. 2) to hold the body portions (1, 3) stationary. Bycoordinating the engagement and disengagement of the feet 5, 5′ with themovement of the forward and rearward members 1, 3 by the hydrauliccylinder 2 and rod 4, the apparatus may propel itself through theconduit 14 in either direction in a stepwise manner.

A rotary cutter or abrasive assembly 6 is mounted at the front of theforward body portion 1 for loosening material so as to clear or cleanthe conduit 14. For removing the loosened material a vacuum is drawnthrough an evacuation tube (not shown) drawn behind the vehicle andconnected to the outlet pipe 9 on the forward body portion 1 which drawsin the material through the opening 8 formed at the base of the plate25. Typically the suction opening 8 is located at the bottom of theconduit travelling apparatus, and thus it is desirable that therotational orientation of the conduit travelling apparatus remains suchthat opening 8 is always present at the bottom of the conduit.

Referring to FIGS. 1 and 2, the wall-engaging arrangement 50 on therearward body portion 3 includes three legs 10 to which respective feet5 are pivotably fixed. Each leg 10 extends generally radially and isfixed by pins 11 for pivoting movement between a retracted position(FIG. 2) and an outwardly extended position (shown in dashed outline inFIG. 2) for engagement with the wall of the conduit 14. A spring 12 forbiasing the legs 10 to the retracted position and a linear actuator 13for extending the legs contact opposing sides of a radially inner end ofeach leg 10. Hydraulic fluid is supplied to the actuator 13 through theflexible hose coil 15 extending from the forward body portion 1. In theextended position it will be understood that the force F applied to therearward body portion 3 (e.g. when the forward body portion 1 is beingdriven forward) provides a self-servo action increasing the frictionalengagement between each foot 5 and the conduit 14.

FIGS. 3 a and 3 b show the wall-engaging arrangement 20 provided forextending the feet 5′ on the forward body portion 1 while simultaneouslyretracting the wheels 17 (see also later), and vice versa. The threefeet 5′ are angularly evenly spaced about the cylinder 2 and are eachpivotally mounted on radially extending pivoting legs 18. Associatedwith each of the legs 18 is a pivoting wheel bracket 19 (lying generallyin the same radial plane as the respective arm 18) to which a pair ofwheels 17 are fixed to support the forward body portion 1 when theforward set of feet 5′ are retracted. The mechanism 20 is actuated by ahydraulic ram 21 having an annular piston 22 ringing the cylinder 2 andfixed thereto for sliding relative to a cylindrical sleeve 23.Pressurising the hydraulic fluid on either side of the piston 22displaces the cylindrical sleeve 23 up or down the cylinder 2 forextending and retracting the feet 5′ and wheels 17. The wall-engagingarrangement 20 includes a yoke 35 pivotally connecting each leg 18 andwheel bracket 19. A fork 36 pivotally connects the yoke 35 and thecylindrical sleeve 23.

Water jets 33 extending from the plate 25 direct a water spray (notshown) at the cutter blade 34 for lubrication, cleaning and aidingremoval of the loosened material. Water is supplied to the forward bodyportion 1 in a hose (not shown). The apparatus is connected by controlcables (not shown) to a remote controller (not shown) connected to thevalve block 38 which incorporates the control valves governing eachoperation of the apparatus. Together with the control cables, water hoseand evacuation tube, elongate hydraulic supply and return lines, (notshown) are bundled together to form an umbilical drawn behind thevehicle and connected to a remote power source and controller (notshown). Preferably programmable-logic-controllers are used in thecontroller to control each of the operations of the apparatus.

In operation, the apparatus may be stepped through the conduit 14drawing the hydraulic lines and cables etc behind it until it reaches anobstruction.

With the front set of feet 5′ retracted and the wheels 17 extended toengage the wall of the conduit 14, the actuator 13 is operated to lockthe rearward body portion 3 in position. The end of the cylinder 2opposing the rod 4 is then pressurised to extend the rod 4 and drive theforward body portion 1 in the forward direction.

The hydraulic ram 21 is operated to fix the forward body portion 1,retracting the wheels 17 and extending the front set of feet 5′. Whenthe rearward body portion 3 is released a return spring (not shown)retracts the rod 4 (or, in a double-acting arrangement the rod end ofthe cylinder 2 is then pressurized to retract the rod 4) to draw therearward body portion 3 in the forward direction.

The valve block 38 includes control valves (not shown) for automaticallyreversing the direction of travel of the rod 4 when it reaches the endof its stroke for controlling its reciprocating movement. Solenoidoperated valves (not shown) control operation of the rams 13 and 21 forselectively engaging the feet 5, 5′, the timing of which in cooperationwith the reciprocation of the rod 4, controls the direction of travel.

When an obstruction is reached, the rearward body portion 3 is fixed andwith the wheels 17 extended the cutter 6 is driven forward to loosen andremove the material encountered. A pressure sensing valve (not shown)reacts to an increase in pressure at the hydraulic motor 7, to reducethe rate at which the cutter 6 is advanced. The apparatus can be removedfrom the conduit by reversing the stepwise mode of travel describedabove.

A second embodiment of the vehicle is illustrated in FIGS. 4-8 and likenumerals are used to refer to like components. The wall-engagingarrangement 50 a on the rearward body portion 3 is also arrangedgenerally symmetrically about the central elongate axis A of thevehicle, the feet being angularly spaced at 120°. The mechanism 50 aextends and retracts the feet 5 a generally radially and includescontrol links 66 for maintaining the wall-engaging face of each foot 5 agenerally parallel to the wall of the pipe. The wall-engagingarrangement 50 a includes three rear legs 10 a angularly spaced, each ofthe legs 10 a being fixed between a pair of control links 66 connectingeach foot 5 a to the rearward body portion 3.

Each leg 10 a is pivotally attached to the foot 5 a at an outer end by afirst pivot 61 and to a mount 62 fixed to the rearward body portion 3 bya second pivot 63. A roller 64 fixed to an inner end of the leg 10 a andthe three rollers 64 are received between two radially-extending flanges69 a, 69 b fixed to the rod 65 of actuator 13 for pivoting the legs 18 aabout their respective second pivots 63 to extend the feet 5 asimultaneously.

Each pair of control links 66 is pivotally attached to the foot 5 a atone end by coaxial third pivots 67 and to the mount 62 at an oppositeend by coaxial fourth pivots 68, the pivots pivoting about parallelaxes.

Hydraulic fluid supply and return hoses 75 are connected between thevalve block 38 and the double-acting actuator 13. The hoses 75 passaround a wheel 76 and are tensioned by the gas spring 77. As in thefirst embodiment, in the extended position the force applied to therearward body portion 3 (e.g. when the forward body portion 1 is beingdriven forward) provides a self-servo action increasing the frictionalengagement between each foot 5 and the conduit 14.

Like the mechanism 50 a, the wall-engaging arrangement 20 a on theforward body portion 1 in the second embodiment of the vehicle extendsand retracts the feet 5 a′ generally radially while employing controllinks 66 a for maintaining the wall-engaging face of feet 5 a′ generallyparallel to the wall of the pipe. The wheel bracket 19 a is pivotablyfixed to the mount 62 a and resiliently connected to the pivoting legs18 a by means of compression spring 70 and bar 71. In this manner thewheels 17 a are firmly pressed against the wall of the pipe when thefront feet 5 a′ are retracted to centralise the cutter 34 in the pipeand provide a reaction against the torque applied to the cutter 34,while allowing the wheels 17 a to ride over small irregularities in thewall of the pipe. The wheel bracket 19 b includes opposed plates 72between which the wheel 17 a and one end of the bar 71 are pivotablyfixed. The opposing end of the bar 71 is received for sliding in a bush73 pivotally connected between a pair of legs 18 a. The compressionspring is received on the bar 71 and captured between the bush 73 andthe pivot on the opposing end.

Each leg 18 a is pivotally attached to the foot 5 a′ at an outer end bya first pivot 61 a and to a mount 62 a fixed to the forward body portion1 by a second pivot 63 a. Each pair of control links 66 a is pivotallyattached to the foot 5 a′ at one end by coaxial third pivots 67 a and tothe mount 62 a at an opposite end by coaxial fourth pivots 68 a, all thepivots 61 a, 63 a, 67 a, 68 a pivoting about parallel axes.

The mechanism 50 a is actuated by a hydraulic ram 21 having an annularpiston 22 ringing the cylinder 2 and fixed thereto for sliding relativeto a cylindrical sleeve 23. Pressurising the hydraulic fluid on eitherside of the piston 22 displaces the cylindrical sleeve 23 up or down thecylinder 2 for extending and retracting the feet 5 a′ and wheels 17. Themechanism 50 a includes a yoke 35 pivotally connecting each leg 18 a andwheel bracket 19 a. Three pairs of links 80 pivotally connect thecylindrical sleeve 23 and an inner end of each leg 18 a.

As seen in FIGS. 7 and 8, the vacuum pipe 9 comprises a forward section9 a and rearward section 9 b slidingly received therein. Thistelescoping action allows the overall length of the machine to bereduced for ready insertion into manholes, or the like, for access todrains. The wall-engaging arrangement s 20 a, 50 a are modular unitssuitable for use in a limited range of pipe diameters and can be readilydemounted from the cylinder 2 and rod 4. The front module 81 includesmechanism 50 a as well as the motor 7 and attached cutter 34 which islocated on a taper 82 and fixed by fasteners (not shown). The rearmodule 83 includes mechanism 20 a connected to plate 84. Tapered portion84 fixed to the rod 4 locates the plate 84 centrally. Pins 85 on theplate 84 have flat heads received through keyhole-shaped apertures (notshown) to mount the module 83 by a push-and-turn action.

Apparatus of a type suitable for implementation of the present inventionhas thus far been described by way of example only, along with typicaluses for which it may be employed.

FIG. 9 illustrates an embodiment of a steerable contact portion 90 whichreplaces the wheels 17 and their mounting axle in the previouslyillustrated embodiments.

The steerable contact portion 90 comprises a carriage portion 91 andcarriage support portion 94. The carriage 91 is pivotably mounted tocarriage support 94 by pivot pin 95, which allows partial rotation ofthe carriage portion 91 about the longitudinal axis of this pin 95.

The carriage portion 91 includes a conduit engaging element 92, whichcomprises a wheel mounted about axle 93. The wheel includes aself-lubricating sealed bearing and an outer tyre portion comprising amildly compressible gripping material, such as a rubber or plasticsmaterial. Treads and other (vehicle) tyre technology may be incorporatedon to the wheel 92 and its outer conduit contacting surface.

Steering is effected by a pair of small rams or actuators 96 (only onevisible, but they are symmetrically positioned either side of pivot pin95) which control the rotation of the carriage portion 91 with respectto the carriage support portion 94.

The steerable contact portion 90 replaces the wheels 17 of the previousillustrations. Pivot pin 97 is positioned in place of the axle forwheels 17. An aperture 98 on the underside of the carriage supportportion 94 allows for connection of a ram or actuator to allow thesteerable contact portion 90 to be raised so that the outer surface ofthe wheel 92 contacts and bears against the inner surface of a conduit.

A set of operable steerable contact portions may be placed on both theforward and rearward travelling body portions 1, 3.

An inclinometer and/or directional sensor (not shown) (as part ofinclination and orientation control means) may be mounted directly tothe body of one or both of the travelling body portions 1, 3. Thecontrol circuitry for the inclination and orientation control means maybe located remotely (with communication by control cables) or mountedsecurely on the body of the conduit travelling apparatus. It isanticipated that this can be achieved by a simple programmable processorcircuit with a set of suitable instructions to control the steeringmechanisms of the apparatus. Remotely located control modules may relyon a laptop, pda, or other computing device to process instructions andoversee control of steerable contact portions 90.

FIG. 10 illustrates a variation of a carriage portion 191 which isconnected to carriage support portion 194 in the manner of FIG. 9. Anactuator 196 is also present, as per the arrangement of FIG. 9, toenable steering control of the carriage 91. A link 201 connects to apivot pin (not shown but equivalent to pin 95 in FIG. 9) to enable thecarriage portion 191 to rotate relative to the carriage support portion194 and thus provide for steering.

A sub-carriage assembly 202 is pivotably attached 212 to the carriageportion 191. There is a substantially parallel link comprising anactuator 203 pivotably attached (205, 206) at each end to the carriageportion 191 and a subcarriage arm 204 respectively. This allows thesubcarriage assembly 202 to be raised and lowered to vary the pressureagainst the conduit's inner surface 210.

Connected to the subcarriage assembly is a skid 212 with two rollers 214which are mounted to the skid 212. A spring mounting system (notvisible) according to standard techniques may be used for the roller 214to skid 212 mounts to accommodate irregularities on the inner surface210 of the conduit.

This arrangement (of FIG. 10) provides an alternative to FIG. 9, alsohaving additional control over the pressure force (governed by actuator203) of the steering's contact engaging elements (i.e. 212, 214) on theinner surface 210 of the conduit.

This may be coupled to the control means which can monitor the change ininclination relative to distance travelled forward. If the change ininclination does not match what it should be for the steering angle anddistance travelled forward, the control means may then do one or morethings (depending on the specific embodiment):

-   -   increase the steering angle (e.g. for embodiments such as shown        in FIGS. 9 and 10);    -   increase the pressure of the steering's contact engaging        elements against the conduit face to counteract slipping (such        as controlling the actuator 203 in embodiments similar to that        of FIG. 10, or increasing the pressure via the actuator        controlling the legs (19) on which the carriages are mounted).

FIG. 11 illustrates schematically a preferred embodiment of a controlsystem. Here an orientation sensor 220 provides information to acontroller 221 about the relative orientation of the apparatus. Thecontroller 221 evaluates this information and determines the degree ofsteering which needs to be applied during the next step forward in orderto bring the pipe travelling apparatus closer to the desired orientationwithin the conduit. It then controls the steering motors 222, orcomponents responsible for effecting steering.

The controller 221 may also, based on feedback, determine whetheradditional corrections to either or both steering angle, and pressure223 of the steering's contact engaging elements are required to effectthe degree of correction calculated.

Aspects of the present invention have been described by way of exampleonly and it should be appreciated that modifications and additions maybe made thereto without departing from the spirit or scope of thepresent invention as described herein.

It should also be understood that the term “comprise” where used hereinis not to be considered to be used in a limiting sense. Accordingly,‘comprise’ does not represent nor define an exclusive set of items, butincludes the possibility of other components and items being added tothe list.

This specification is also based on the understanding of the inventorregarding the prior art. The prior art description should not beregarded as being authoritative disclosure on the true state of theprior art but rather as referencing considerations brought to the mindand attention of the inventor when developing this invention.

1-17. (canceled)
 18. Conduit travelling apparatus for travelling througha conduit, said conduit travelling apparatus comprising two travellingbody portions, each with associated wall engaging clamping means, andsaid travelling body portions connected by extensible drive meanscapable of moving said travelling body portions towards and away fromeach other; at least one said travelling body portion including at leastone steerable contact portion which can be brought to bear against theinside of a conduit as the travelling body portion moves with respect tothe conduit; a said steerable contact portion including at least oneconduit engaging element for contacting an inner surface of saidconduit; the arrangement being such that said conduit engaging elementcan exert a steering force against said inner surface of the conduitwhen its carriage portion bears against and travels along same; theconduit travelling apparatus including and/or communicable withinclination and orientation control means comprising inclinationdetermining means, for determining the rotational inclination of theconduit travelling apparatus; said inclination and orientation controlmeans consequently controlling one or more said steerable contactportions associated with the conduit travelling apparatus.
 19. A conduittravelling vehicle as claimed in claim 18 having an extensible body inwhich: said two travelling body portions comprise a forward body portionand a rearward body portion separated by a powered telescopingconnection of variable and controllable length, the powered telescopingconnection characterized that the distance between said forward andrearward body portions is controllably alterable; each of said forwardbody portion and rearward body portion including a wall-engagingmechanism; each wall engaging mechanism comprising a plurality ofradially pivotable legs, each connected to a said body portion at oneend and having a wall-engaging foot at the distal end; for each wallengaging mechanism, all of the radially pivotable legs with wallengaging feet connecting to a common actuator, said common actuatorcontrolling the radially extended position of said radially pivotablelegs between retracted and extended positions; the wall engagingmechanism on either or both of said forward and rearward body portionsincluding at least one retractable wheel arrangement, a said retractablewheel arrangement comprising a plurality of wall engageable wheelassemblies each coupled to a radially pivoting wheel bracket; saidradially pivotable legs and said radially pivoting wheel brackets of awall engaging mechanism coupled, the coupling preventing both of i) saidradially pivotable legs and ii) said radially pivoting wheel bracketsbeing simultaneously in a fully radially extended position.
 20. Conduittravelling apparatus as claimed in claim 18 in which there isinclination determining means associated with each said travelling bodyportion.
 21. Conduit travelling apparatus as claimed in claim 18 inwhich the inclination and orientation control means determines therotational inclination of the conduit travelling apparatus relative toone or more preferred reference orientations.
 22. Conduit travellingapparatus as claimed in claim 21 in which a preferred referenceorientation comprises either or both a true horizontal, or a truevertical.
 23. Conduit travelling apparatus as claimed in claim 18 inwhich the inclination and orientation control means determines thesteering action required to correct the rotational inclination of theconduit travelling apparatus towards a preferred rotational inclination.24. Conduit travelling apparatus as claimed in claim 18 in which thereis controllable steering drive means associated with a said steerablecontact portion.
 25. Conduit travelling apparatus as claimed in claim 24in which a said controllable steering drive means is driven by one ormethods in the following list: hydraulically powered, electricallypowered, and pneumatically powered.
 26. Conduit travelling apparatus asclaimed in claim 18 in which a conduit engaging element is pivotablyconnected to a steerable contact portion, to provide a steering action.27. Conduit travelling apparatus as claimed in claim 18 in which asteerable contact portion comprises a carriage.
 28. Conduit travellingapparatus as claimed in claim 18 in which a steerable contact portion ispivotably connected to a travelling body portion so as to provide asteering action.
 29. Conduit travelling apparatus as claimed in claim 18in which a conduit engaging element comprises one or more members forthe following list of engaging elements: wheels, rollers, rotating trackassemblies, and skids.
 30. Conduit travelling apparatus as claimed inclaim 18 in which the inclination and orientation control means eitheror both continuously or repetitively adjusts the degree of steering of asteerable contact portion during motion of a travelling body portion.31. Conduit travelling apparatus as claimed in claim 18 in which eitheror both of a steerable contact portion and conduit engaging element isretractable so as to not engage an inner surface of said conduit. 32.Conduit travelling apparatus as claimed in claim 18 in which thepressure by which a conduit engaging element bears against an innersurface of the conduit can be varied.
 33. Conduit travelling apparatusas claimed in claim 18 in which the inclination and orientation controlmeans adjusts the pressure by which a conduit engaging element bearsagainst an inner surface of the conduit as part of its control over thesteering and changing of the inclination of a travelling body portion.